[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Jeholornis prima discussion



MariusRomanus@aol.com wrote-

> Ok...... I am now lost..... and need to ask...... So where are we putting
the
> tyrannosaurs now adays and why???

Outside Maniraptoriformes (Arctometatarsalia + Maniraptora) if you ask-
Maryanska et al. 2002
Norell et al. 2001
Holtz 2001
Longrich 2001
Rauhut 2000
me 1999-2000
Sues and Makovicky 1998
Forster et al. 1998

Inside Maniraptora, sister to Avepectora if you ask-
Sereno 1999

I don't think anyone supports arctometatarsalian tyrannosaurids anymore....

As for why, let's use Norell et al.'s (2001) character list to see why they
were excluded from Maniraptoriformes (called Coelurosauria in their paper
grrrr....) in their study.  Note I do not agree with all of these and will
comment on some that I have examined for my big analysis.  There are usually
several exceptions to these characters, but I list only those that would
potentially affect where the character state changes (so the fact
dromaeosaurids lack several of these is not mentioned because it would be a
reversal in any reasonable phylogeny).  Tyrannosaurids lack the following
maniraptoriform synapomorphies-
1. maxillary fenestra situated posterior to anterior border of antorbital
fossa
2. round orbit
3. exits of cranial nerves X-XII flush with surface of exoccipital
4. basipterygoid recesses on dorsolateral surfaces of basipterygoid
processes absent
(isn't this what Stokesosaurus and Itemirus have?)
5. subotic recess present
6. dorsal tympanic recess present
7. no lacrimal crests
(a lacrimal crest is present in Pelecanimimus)
8. no enlarged lacrimal foramina
9. palatine and ectopterygoid contact
10. coronoid reduced or absent
(I don't see a size difference between tyrannosaurid and dromaeosaurid
coronoids)
11. interdental plates fused/absent
(also in basal tyrannosauroids, but not in segnosaurs, Bagaraatan and maybe
Caudipteryx)
12. axial epipophyses not extending posteriorly past postzygopophyses
13. axial neural spine compressed mediolaterally
(also in Eotyrannus- Hutt et al. 2000)
14. cervical epipophyses placed anterior to postzygopophyseal facets
(not in non-oviraptorosaurian enigmosaurs)
15. anterior cervical centra extending posteriorly past neural arch
(only valid for third and fourth cervicals- Makovicky, 1995)
16. anterior cervical centra distinctly wider than high
(only valid for third and fourth cervicals- Makovicky, 1995)
17. scars for dorsal interspinous ligaments terminate below apex of neural
spine
18. ventral surface of sacral centra flattened, sometimes with sulcus
19. proximal ends of proximal chevrons elongate anteroposteriorly and
flattened
(ornithomimids seem to lack this)
20. cervical ribs broad and shorter than vertebrae
21. elongate posteroventral process on coracoid
I also have some confidential information on a relevent taxon that makes two
characters less valid.

Mickey Mortimer